WHEAT:NEWS Volume 6, No. 6

Whether it's about flinging packets through the air on bursts of microwave energy or sending them out to mobile devices via the Internet, it's all about getting your message out there.

This month in WHEAT:NEWS we'll bring you a no-nonsense guide to podcasting, a bit of guidance on licensed microwave IP STLs, a look at an unusual application of Wheatstone's ACI protocol by a third-party software developer, and a look around the factory's test areas where several systems are about to ship.

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No BS Guide to Radio Podcasting

Amateur podcasters can call them what they want, but between us broadcasters, we know those so-called subscribers are really listeners with earbuds and a cellphone.

And that means we can reach them like we usually do -- through their ears.

No one knows those ears better than broadcasters. We know about good content and good sound. What’s new to us are the codecs and the listening environments and devices used for podcasts. To explain what it all means, we asked our audio pros Jeff Keith and Mike Erickson to give us a quick sound check on podcasting.

Oh, the places they go, the things they do

The iPhone, Android and other smartphones are skewed to the vocal range for obvious reasons. Subtract from this equation the codec bit-rate reduction needed to get that sound to those earbuds, not to mention all that background noise your listeners are subjected to while listening on the move, and there’s no way you should hand them a full dynamic range of sound.

Removing program content that can’t be heard by these devices will improve the subjective quality of your audio. Jeff suggests that anything below 100Hz and above 12kHz won’t be missed. In fact, he says, “Removing those frequencies might actually help your sound, due to reduced or removed ‘codec teasers’ such as hiss or hum.”

For all those other unwanted frequencies that happen during pauses in programming or when the AC kicks on during a recording, you’ll need a noise gate same as any other program production. Any good mic processor (such as our M1, M2 or M4-IP mic processors) should have a noise gate to keep the noise floor from rising during pauses in vocal content. This, too, will give the codec less nonsense to work with and turn into noise.

Processing to the codec

Unlike processing your on-air signal in which modulation control is the goal, processing for podcasting is all about controlling what the codec sees. This is why it’s important to give the codec consistent levels and a balanced left and right, especially at lower codec bitrates. Jeff recommends switching from stereo to mono for podcasts at bitrates less than 48kbps in order to preserve audio quality. The ideal is to maintain consistency going in, although often some audio processing can be helpful to smooth out level variations than can cause the codec to overwork. Avoid overly boosted highs, any noticeable hiss or hum, and distortion due to badly clipped audio, all of which adds to the codec’s work (and bit) load.

Adding a trace of AGC or compression can add a measure of “presence” to a podcast, but careful. Keep in mind that many of your podcast listeners will be listening in on headphones, and too much compression this close to the ear could cause fatigue. Others will be listening to longer form podcasts through their sound system in the car, all the more reason why processing that isn’t fatiguing is important.

How aggressive should you set the processing for podcasting? Mike says just enough to raise the audio above any ambient noise for listeners who don't have noise cancelling headphones, but not so much that you remove all trace of quality for those who are downloading low bitrate podcasts.

Most any audio processor that you have in the chain will work. But if you have a choice, use a processor like our Aura8-IP processing BLADE (which has eight separate multiband processors, one of which you can use for podcasting). It lets you selectively add AGC, compression or limiting by bypassing the other sections, rather than require all three functions to operate interdependently. This selectivity makes it a little less tricky to get the right amount and type of processing needed.

For more information on processing for the Internet, download Jeff Keith’s white paper, "Audio Transfer Through the Internet." Wheatstone also introduced a new Audioarts console (our new Audioarts 08 has USB and balanced or unbalanced stereo mixing bus) made for podcasting that is worth checking out if you plan to set up a separate sound booth or studio for podcasts.

Your Cheat Sheet to Part 101 Wireless IP STLs

Part 101 frequencies have been used by businesses and others for some time. But not until 2011, when the FCC abolished the so-called “last link rule” precluding broadcasters from using these bands, did broadcasters have access to these frequencies for wireless IP STLs.

Licensed IP wireless systems (Part 101 6 GHz or 11 GHz) are useful as a main STL, such as when a station is moving and re-upping their STL in a market where 950 MHz frequencies are hard to get.

By putting up an IP link from the studio to the transmitter, your transmitter site immediately becomes part of your Ethernet network. “It’s almost like from an IP standpoint, that tower is sitting as part of your building now,” said Jeff Holdenrid, who specializes in wireless IP for broadcast and other emerging markets for DoubleRadius engineering firm. Jeff has installed dozens of wireless IP microwave systems with our WheatNet-IP audio network in the past five years, most averaging in the 20 to 25 mile range.

A WheatNet-IP IP88D BLADE into an IP wireless radio can run 8 stereo channels across a wireless IP link and still have enough bandwidth left over for video surveillance, VoIP, remote control and other periphery functions.

A licensed-frequency system is likely to be full duplex and its throughput consistent. A 100 Mbps IP wireless radio on a licensed frequency will operate at 100 Mbps whether its range is six miles or 20 miles.

One of the reasons licensed-frequency IP wireless radios are able to maintain throughput is because of adaptive modulation. “Whereas most Part 74 radios are on or off, they work or don’t, in the IP world they work at a slower speed. They’ll slow down to stay alive. That’s another advantage of what they do. If you have a 100 meg radio, and only need 50 megs, you have room to step down,” explains Jeff.

Planning for Throughput

But while greater output power doesn’t necessarily mean that you can go farther, it does often mean better signal strength and subsequently, being able to drop down in dish size to put less load on the tower. “If you’re renting space on a tower, and you can get away with a 4’ dish instead of a 6’, you’ve just saved thousands a month in rental fees for tower space,” says Jeff.

To determine how much throughput you’ll need for a licensed or unlicensed system, Jeff suggests you start with 100 Mbps per station and then add on current requirements such as whether or not you’ll need VoIP capability or video surveillance transmitted back from the transmitter site. He recommends planning for another 20 to 40 percent above that for any new requirements bound to pop up in the next several years.

Some of the unlicensed IP wireless radios and all of the licensed radios provide software upgrades that let you scale up in throughput, starting at 250 Mbps and scaling up to as much as 1 gigabit.

Licensing for Part 101

Applying for Part 101 licensed frequency for your wireless IP STL is fairly straightforward and quick. “We do a PCN – power coordination notice – just like they traditionally do with 7 gig, 13 or 950. We find channels available and issue a PCN. Once the PCN is clear, which usually takes two to four weeks, then you file. Once you file, as long as you’re not within 10 miles of a U.S. border, meaning Canada or Mexico, you have conditional approval to start operating,” comments Jeff, who says in most markets, frequencies are readily available.

Installing Part 101 Systems

For Part 101 systems, there are three different setups: all indoors, where 100 percent of the electronics and radio components are indoors and you run flexible waveguide cable up the tower to the antennas. These installs are a lot like traditional Part 74s, and can get somewhat pricey. A step down is the split system, where the radio is located up near the antenna, but the connections – Ethernet, fiber and T1 connections - are on the ground, which brings down your cost. All-outdoor installations are when 100 percent of the equipment is on the tower, which lowers costs even more.

Clocking In with ACI

Our Kelly Parker ran across VClock made by Voceware recently, and thought it was pure genius. There are plenty of virtual clocks that are merely numbers on a wall, or virtual clocks that are designed specifically for one broadcast group only. This virtual clock is different. VClock is flexible like a certain audio network we know, so it can transform from just a single clock to a network of clocks taking in information from different sites. Everything on it is configurable, complete with up to 32 lamps that are changeable and can be turned on / off or made to flash with external triggers (such as a "mic live" signal from a mixing console or a phone call). This clock also has an embedded web browser, which allows you to show any content that you like on VClock, simply by creating a web page.

Of course, one thing led to another, and VClock is now one of our third-party add-ons that communicate to the WheatNet-IP audio network through the ACI protocol. That is, from any control panel, workstation or control surface in the WheatNet-IP network, you can trigger salvos within VClock that change its features. VClock interfaces directly into the port of an I/O BLADE access unit through ACI for IP connectivity to our SLIOs.

ACI is our control interface used by automation companies like ENCO, OMT Technologies, RCS and WideOrbit to tightly integrate WheatNet-IP audio networking with automation functions.

A Stroll Through Club Wheat

Raw materials arrive in the back door and wind through the factory to be pressed, molded, wired and tested, retested, and tested again before becoming Wheatstone or Audioarts products. We do just about everything here in our New Bern, North Carolina factory, including machining, fabrication, screening and surface mounting to printed circuit boards. This is why we’re able to keep the quality high and the cost reasonable, plus build-to-order and develop new products faster than the other guys.

Jay Tyler took a stroll through Club Wheat recently with camera in hand.

Video: FM-55/FM-25 Quick Start with Mike Erickson

In this ten minute video, Wheatstone engineer Mike Erickson takes you through the initial setup of the FM-55 processor from out of the box to on-the-air. These instructions also apply to the FM-55's little sister, the FM-25.

Wheatstone

Power Group (Istanbul, Turkey) purchased L-12, L-8 and SideBoard control surfaces with a WheatNet-IP audio network through Radikal Elektronik Ltd.

Rogers Kitchener Radio Group (Kitchener, ON) purchased an LX-24 control surface, IP-12 digital console, two M4-IP four channel mic processor BLADEs, four TS-4 talent stations and Glass E virtual mixer as part of a WheatNet-IP audio network.